slimes are just hard to find, and clearlag is so stupid that it deletes minecarts, boats, paintings and occasionally hostile mobs
No. Slimes only spawn in y=50 to y=70 in a swamp biome. I don't see the point of trying to find one when you can make it above ground lol then again the spawning of the slimes is based on the moon pattern blah blah blah
For Slimes to Spawn they need to be between Y:50 and Y:70 in a swamp biome(light level 7 or less) or below Y:40 in a specific slime chunk(any light level) in anyother biome. And clearlag takes the minecarts because too many minecarts create lag. Any other questions about slimes check to see if your answer is here: http://minecraft.gamepedia.com/Slime